The present invention relates generally to an apparatus for controlling the power generation of an alternating current generator (hereafter referred to as an A-C generator) for use in a vehicle and, more particularly, to an apparatus for controlling the output current of the A-C generator by controlling the field current thereof independently of the field current control by the detection of the output voltage of the A-C generator.
In a conventional vehicle alternating generator system, it is a known practice to decrease the output voltage of the generator for the purpose of temporarily reducing the driving torque thereof or suppressing an excessive temperature rise during the power generating operation.
With such a conventional control system, however, as the output current of the power generator may vary depending upon the state of a power storage battery and of an electric load owing to the voltage limitation of the output of the power generator, the conventional control system is not fully satisfactory for controlling the output of the generator.
Also, when the operating temperature of the power generator becomes excessively high, the power generator is disconnected from the load so that power supplied to the electric load of the vehicle is only from the vehicle storage battery, thus causing the battery to be unnecessarily discharged, whereby the voltage of the power source of the vehicle is lowered. A low power source voltage may inadvertently have an effect on various electronic devices provided in recent designed vehicles, and to avoid the lower source voltage necessitates the installation of a large capacity storage battery.
On the other hand, Japanese Publication No. 59-47532 disclosed a battery charging apparatus including a battery charged through a rectifier by the output of an A-C generator having a field coil, and a voltage regulator for regulating the output voltage of the generator at a constant value by controlling the field current. Particularly in this apparatus, at least one temperature sensor and a protecting unit are additionally provided. When the sensor senses the temperature of the rectifier and the voltage regulator or parts thereof being heated in excess of a preset value, the protecting unit controls the current flowing through the field coil to reduce or interrupt the output of the generator.